Foueth to samuel vanness



(No Model.) 2` Sheets-Sheet 1.

M. MooMmn-HON.- Compound Steam Engine.

' No. 238,241. Patented March `1, 1\&81`.

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NPEYB`S, PHOTO-LITHDGRAPHUL WASHINGTON. D C4 (No Model.)

M. M610 MAHON. Compound Steam Engine.

38,241. Jil/l Patented March 11,1881.

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UNITED STATES PATENT EEICE.

MIOHEAL MAGMAHON, OF BROOKLYN, NEW YORK, ASSIGNOR OF ONE- FOURTH TO SAMUEL VANNESS, OF SAME PLAGE.

COMPOUND STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent No. 238,241, dated March 1, 1881.

imputation med June 1c, 1880. (No model.)

To all whom it may concern:

Be it known that I, MIGHEAL MACMAHON, of Brooklyn, in the county of Kings and State of New York, have invented a new and Improved Equilibrium-Piston Compound Steam- Engine, of which the following is a specification.

This invention relates to that class of steamengines in which, by the arrangement and operation of suitable valves and ports, the eX- haust-steam is con ducted from the one to the otherside of the piston, and into a communicating low-pressure or vacuum cylinder, for the purpose of equalizing the pressure upon the said piston.

The invention consists of a three-cylindered engine, two of which are called the high-pressure7 cylinders, and the third and larger one the low-pressure77 or vacuum77 cylinder'. The high-pressure cylinders receive i steam direct from the boiler, but only in one end of each. The pistonsof both these high-pressure cylinders are on one rod, which rod is connected to a crank directly opposite the crank of the lowpressure cylinder, and by the admission ot' steam to the opposite or extreme end of each alternately a similar action to that ot' a single cylinder admitting steam alternately above and below the piston is obtained but the similarity ceases there, as in all other respects the action of the steam in these cylinders dit'- fers from the action of the steam in the highpressure cylinder of the present form of compound engine.

Steam being admitted to either high-pressure cylinder', it is cut oft and allowed to expand in the usual manner; but, instead ot exhausting directly into the low-pressure cylinder, it exhausts iirst into the opposite end ot' said high-pressure cylinder, and enters the low-pressure cylinder at the proper instant of time for lead,77 the valvesof both cylinders being constructed and set especially with the View of securing the proper distribution of the steam. The steam then continues, during the whole period of exhaust,`to entirely fill this first high-pressure cylinder above and below the piston, said piston undergoing all the variations of pressure due to the expansion of the steam through its admission to the lowpressure cylinder, and these variations take place equally on both sides of the rst highpressure piston'at the same instant of time, and consequently said piston is in equilibrio during all the time ot' exhaust to the lowpressnre cylinder, and being on the same rod with the second high-pressure piston next receiving steam from the boiler, and whose lower side is in communication with a condenser, the said rst high-pressure piston meets with no resistance to its motion. At the proper' time for lead in relation to the stroke ot' the engine, this second high-pressure cylinder receives steam to produce the returnstroke to complete the revolution; but having yet to deal with the first admission of steam from the boiler, it is necessary to remember that the second admission ot' steam (the first admission into the second high-pressure cylinder) is really actuating the piston which received the first steam, as well as the piston on which it is now acting directly, and that this first piston is now in equilibrio, permitting both itself' and the second piston to heimpelled with all the force due to the full effective pressure of the steam admitted into the second cylinder, less whatever back-pressure is due to the uncondensed steam remainingin the condenser above a perfect vacuum, the under side of the second piston being, as stated, in communication with a condenser. Following this first admission ot' steam in its action until it enters the condenser will serve to show the act-ion of steam in the' second` cylinder, and thereafter in both. The iirst supply ofsteam, having gone through its usual course of admission, cut-olf, and expansion in one end of the first cylinder, is allowed, having completed a half-stroke of the engine,

to exhaust into the opposite end of said cylin-y by 4the valve, and said tirst high-pressure cylinder is again ready to receive steam from the boiler. In the meantime the communication between the low-pressure cylinder and that IOO end of the first high-pressure cylinder which is not in connection'A with the boiler remains open, and the time the exhaust to the condenser commences both low-pressure and irst high pressure pistons are being simultaneously and equally affected by the partial vacuum produced in the condenser; and thus what is usually called the high-pressure7 cylinder, in contradistinction to the condensing-cylinder, becomes, in effect, a condensing-cylinder, effectually eliminating back-pressure and substituting an approximate vacuum instead, and so enabling the area of its piston to be added to the area of the low-pressure piston during condensation, for effective work, in addition to the advantage obtained by the absence of backpressure, and securing, also, a further gain of mean absolute pressure of steam on the lowpressure piston, a pressure due to the terminal pressure of steam in the high-pressure cylinder becoming the initial pressure in the lowpressure cylinder.

The manner in which the steam from the high-pressure cylinders enters 4the low-pressure cylinder secures the advantage derived from perfect continued expansion, thereby giving to both high-pressure cylinders of this compound engine all the important features possessed by a single-cylinder engine, while still retaining the superior features of the compound engine.

The distribution of the steam in the highpressure cylinders is effected and controlled by valves of the usual construction provided with cut-off plates sliding on the backs thereof; but the distribution of the steam to the low-pressure cylinder is effected by means of an improved balance-valve sliding between the face of the cylinder and the face of a Valve suspended upon a bolt in the valve-chest cover, as shown in the drawings.

Figure l is a front elevation of the engine, partly in section. Fig. 2 is a side elevation of the same, partly in section. Fig. 3 is a vertical sectional elevation of a portion of the engine on line a: Fig. 2. Fig. 4 is a vertical sectional elevation of a portion of the engine on line y y, Fig. 2. Fig. 5 represents a transverse section on line z z, Fig. 2.

Similar letters of reference indicate corresponding parts. v

In the drawings, Arepresents the bed-plate;

B, the journal-boxes for the double crank-shaft C, and D D' represent the standards. The standards D support the high-pressure cylinders E E', that are set one above theother and their respective valve-chests F F', while the standards D' support the low-pressure cylinder G and its valve-chest G'.

H is the piston-rod common to the two highpressure cylinders E E', and having secured on it the respective high-pressure pistons. H' is the cross-head, moving in the ordinary manner between guides a of the standard D; and H" is the pitman connecting said piston-rod I-I with a crank of the driving crank-shaft C, as shown.

I is the piston-rod of the low-pressure cylinder G, and having fixed on it the low-pressure piston G". I he piston-rod I is provided with a cross-head moving in the ordinary manner between guides b of the standards D', and with a pitrnan connecting said piston-rod I with a crank of the drivin g-shaft C, opposite the crank to which the piston-rod H is connected.

The valves L L' of the high-pressure cylinders E E', respectively, are fixed and adj usted in the usual manner by nuts c c, on the valverod L", which valve-rod passes down through suitable stuffing-boxes d and tube el', and has its lower end engaged with a lever, f, that is rigidly fixed on the horizontal rock-shaft M, whose end crank, g, is connected with a sliding block, h, that moves in the slot of the link M' as the latter is adjusted by the lever M", that is pivoted on the lug t' through the medium of the rod 7c and pin k'. The sa'id link M', the eccentrics m m, that are keyed on the driving-shaft C l, and the rods m' m', (one for the forward and the other for the backward movement of the engine,) that are connected to the respective ends of the link M', constitute the link-motion for reversing the engine, and. the controllinglever M istretained in any position that may be given to it by the engagement of its sliding spring-rod m" in the notched segment-bar M'.

N is the cut-off valve-rod, provided with right and left screws a a, for the adjustment of the sliding-valve plates N' N', that move on the backs of the slide-valves L L'. Said rod N is arranged parallel with the valverod L", and passes through suitable stuffing'- boxes a' n', tube el', and valve-chest F F', and is connected at its lower end to a cross-head, N", Within which it turns, said turning. being effected by means of a pinion, N within which said rod N has also a vertical sliding motion fixed on the upper end of saidrod and operated by a movable rack, N"", as shown. The cross head N" obtains motion through the connecting-links O and lever O', which latter is movable on the rock-shaft M, which are actuated by the eccentric, eccentric-rod,

IIO

and lever 0", the eccentric of this combination being secured on the shaft C. The links O are severally suspended from or attached to the two opposite arms of the cross-head N. The rock-shaft M also operates,'through the connectin g-lever I" and link P", the valve-rod P of the low-pressure cylinder balanced valve P'. This balanced valve 1.3"' is held against the face of the low-pressure cylinder Gby means of the valve-plate Q, that is suspended by the bolt g, which passes centrally through the valve-chest cover Q'. This valve-plate Q is retained in its vertical position by means of the projections q' on the back of the slide-valve P', which latter is held in a vertical position in the usual manner. rj he valve-chest cover Q' is provided with two cylindrical projections, Q", Within which are fitted steam-tight pistons Q' that are pressed against the back of the suspended valve-plate Q by steam admitted from the boiler against the back of lsaid pistons Q through the openings g" in the said projections Q, thereby keeping the valveplate Q pressed closely upon the back of the valve P, and the latter steam-tight against its seat.

In lieu of the steam actuated pistons Q, springs may be used for the purpose of holding the valve-plate and valve steam-tight against their respective seats.

The parts being in position shown in Figs. 3 and 4, and steam being admitted to the valvechests F F of the high-pressure cylinders, the steam enters through the valve L and port of the cylinder E, and having driven the piston E to the end of the stroke, the piston G ofthe low-pressure cylinder G at the same time being moved in the opposite direction, the position of the valve L is changed, and the steam is permitted to exhaust through the port l, into the ports 2 3, and from port 2 through the sliding valve P to port 4, and thence into low-pressure cylinder G, above the piston G, where said exhaust-steam then forces the piston G to the end ofthe stroke. Then the reversal of the movement of the valve P opens a communication between the upper end ofthe cylinder G and the lower end of the cylinder E, and simultaneously into the condenser that is designed to be connected with the engine, and the steam from` the cylinder G then escapes through port 4, and at the same time from the cylinder E through ports 2 5 6 into the valve-chest G, whence it passes to the condenser through port 7. 0n the return-stroke of the engine a similar movement and action of the steam occurs in connection with the cylinders G and E, and their respective parts.

Having thus fully described my invention, I claim as new and desire to secure by Letters Patentl. The combination, with the high-pressure steam-cylinders E E', provided with suitable pistons, ports, and valves, and a common piston-rod, ot the low-pressure cylinder G, connected therewith by steam-passages and provided with slidevalve plate and valve Pf, suspended valve-plate Q, and valve-pistons Q, substantially as herein shown and described.

2. In asteam-engine, the combination, with the sliding valve P, provided with back projections q, of the suspended valve-plate Q and pistons Q, substantially as herein shown and described, whereby said valve-plate and valve are held steam-tight in their respective seats, as set forth.

3. In a compound steam-engine, the combination, with the low-pressure cylinder G and valve-ch est G', provided with valve-chest cover Q', having cylindrical perforated projections Q, ot the piston Q and suspended valveplate Q, substantially as herein shown and described.

MIGHEAL MACMAHON.

Witnesses:

J.VH. ScARBoRoUGH, C. SEDGWICK. 

